Amphilophus lyonsi

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Amphilophus lyonsi is a medium-to-large Central American cichlid associated with the Río Tempisque basin in Guanacaste Province, Costa Rica. It is less common in the aquarium trade than several better-known Central American cichlids, making it appealing to aquarists interested in a more regional and less frequently offered species. Its powerful body, territorial behavior, and ability to move substrate reflect the general requirements of larger cichlids. A spacious aquarium, effective filtration, and a sturdy layout are important, especially if a pair forms and begins breeding. Its moderate rarity also makes responsible sourcing and careful long-term planning particularly worthwhile.

General species description

Amphilophus lyonsi is a robust medium-to-large cichlid suited to Central American biotope aquariums. It can become strongly territorial, particularly during breeding, and may rearrange the layout by digging in the substrate. Its care requires more space and stability than that of a small community cichlid. The species is generally uncommon to moderately rare in the aquarium trade and is better suited to aquarists experienced with larger cichlids. A structured aquarium with visual barriers can reduce constant disputes. Tankmates should be selected according to similar size, temperament, and water requirements. Careful observation remains essential because individual behavior can vary considerably.

Geographic origin and biotope

Amphilophus lyonsi originates from Costa Rica, specifically the Pacific-slope drainage associated with the Río Tempisque in Guanacaste. Its habitat includes slow to moderately flowing sections, pools, margins, and areas with sand, mud, or small gravel. Riparian vegetation can provide shade and cover, while branches and stones structure the shoreline. In an aquarium, clean, well-oxygenated, moderately alkaline water is preferable to a delicate heavily planted layout, since the species may move substrate and uproot plants. A natural arrangement of wood, rockwork, and open bottom areas better reflects its behavior and makes territorial boundaries easier to establish.

Precise location and local name

The species is associated with the Río Tempisque drainage in Guanacaste Province, northwestern Costa Rica. The most widely used English vernacular name is Lyons’ cichlid; in French, it is commonly rendered as cichlidé de Lyons. It is not associated with a widely standardized Spanish local name in aquarium use. Its relatively restricted distribution makes it an interesting choice for a biogeographic aquarium devoted to the Pacific waters of Costa Rica. When maintaining or breeding it, obtaining fish with reliable locality information is valuable, particularly for aquarists interested in preserving geographic identity within captive lines.

Appearance and physical characteristics

Amphilophus lyonsi has a deep, powerful body, a broad head, and a mouth suited to varied foods and substrate excavation. The base coloration is usually grayish to brownish, with darker markings that vary with age, mood, and social context. The fins may show yellowish or reddish tones, especially in mature fish displaying breeding condition. Its compact profile and powerful jaws are characteristic of a bottom-working cichlid. Pattern intensity can change quickly in response to stress, dominance, or territory defense. Mature specimens have an imposing presence even though they are generally less brightly colored than many commercially selected cichlids. A durable layout is therefore important for both appearance and safety.

General diet

Amphilophus lyonsi is omnivorous and benefits from a varied diet based on quality pellets for large cichlids, vegetable foods, and frozen items. Meals may include shrimp, krill, worms, or other meaty foods, offered in moderation. Regular vegetable matter helps provide dietary variety for a cichlid that explores the bottom and available surfaces. Avoid excessive fatty foods and feeder fish from uncertain sources. Controlled portions, offered once or twice daily to adults, help maintain good condition and stable water quality. The diet should remain **varied** and support steady growth rather than forced rapid growth. Removing uneaten food is especially useful because large cichlids can produce a significant organic load.

Essential data

• Native river: Río Tempisque
• Local name used: Lyons’ cichlid
• Origin of the scientific name: Amphilophus is the genus name; lyonsi is a specific epithet formed from the name Lyons.
• Full-name etymology: Amphilophus comes from Greek roots referring to a crest or double-edged structure; lyonsi is a Latinized proper name honoring Lyons.
• Common/vernacular names: Lyons’ cichlid; cichlidé de Lyons
• Family: Cichlidae
• Subfamily: Cichlinae
• Name pronunciation: am-fill-oh-fus lie-on-see
• Discovery: William A. Bussing, 1989
• Maximum adult size: About 20 cm
• Water temperature and pH: 24–29 °C; pH 7.0–8.2
• Stream appearance and surrounding vegetation: Slow to moderately flowing areas, shaded margins, branches, stones, and riparian vegetation.
• Typical tankmates: Amphilophus citrinellus, Amphilophus trimaculatus, Parachromis friedrichsthalii
• Temperament and behavior: Territorial, substrate-moving, and potentially aggressive, especially as a pair or during breeding.
• Water depth: Margins, pools, and shallow to intermediate areas.
• Sexual dimorphism: External differences are variable; mature males may become larger and more heavily built.
• Bottom structure and flow: Sand, mud, gravel, and woody debris; slow to moderate current.

In your aquarium

For successful care of Amphilophus lyonsi, provide a large aquarium, firmly secured décor, and filtration capable of handling the organic load of a large cichlid. Stable water, a varied diet, and regular water changes are essential. Avoid small, peaceful fish that may be harassed or swallowed. Breeding can greatly increase territorial behavior, so visual barriers and a backup relocation plan are useful. Respecting geographic origin and purchasing through a responsible source also supports the conservation value of this relatively uncommon species. With adequate space, durable décor, and attentive management, it can become a rewarding long-term Central American cichlid.